"For among these, the first and chief consideration is the size of the sphere of the fixed stars, which is immense, and the next is the size of the earth, which is as a point in comparison with the hea…"

"The sphere is the most perfect of all figures, hence it is the form of the world."

"For it is manifest that the movements of the planets are not uniform, but sometimes faster, sometimes slower, sometimes direct, sometimes retrograde."

"When, therefore, I had long considered the uncertainty of the traditional mathematical doctrines concerning the order of the spheres of the universe, I began to be annoyed that no more accurate explan…"

"The order of the planets is this: Saturn, Jupiter, Mars, Earth, Venus, Mercury."